Sightings of endangered shortnose sturgeon in Damariscotta Mills in early January have caught the attention of a scientist with the Maine Department of Marine Resources.
DMR scientist Gail Wippelhauser studies striped bass and sturgeon, among other species. The fish spotted at the base of the Damariscotta Mills fish ladder were probably shortnose sturgeon, she said, rather than the larger Atlantic sturgeon.
Shortnose sturgeon spawn in fresh water in the Androscoggin and Kennebec rivers, according to Wippelhauser, and frequent the Penobscot River.
According to the National Marine Fisheries Service, the species has also been documented in the Damariscotta, Medomak, and Sheepscot rivers.
Scientists have detected tagged sturgeon “much further down” toward the Damariscotta’s mouth, but never in Great Salt Bay or Damariscotta Mills, Wippelhauser said.
“I was not aware that they were that far up into the Damariscotta,” she said. She called the sightings “very exciting.”
Damariscotta River Association Director of Education and Environmental Monitoring Sarah Gladu has heard anecdotal reports and seen studies indicating “intermittent visits” by Atlantic sturgeon to the lower river.
“I had never heard of sturgeon near the fish ladder before this sighting,” she said.
Since the news, Wippelhauser has spoken with at least one resident who reported regular sightings of sturgeon in Great Salt Bay. She suspects the fish may be wintering in the bay.
The sturgeon may have moved to the base of the fish ladder to find fresh water. Shortnose sturgeon usually winter in fresh water, staying on the bottom in one place, according to Wippelhauser.
The fish are unlikely, however, to climb the fish ladder into Damariscotta Lake.
“There’s no evidence that they’ve ever used fish ladders,” Wippelhauser said.
Gladu concurred. “The pools aren’t even big enough for this fish to use,” she said.
Wippelhauser would like to catch the sturgeon at Damariscotta Mills. Scientists would measure and weigh the fish, implant tags in the fish to allow for identification in the event of recapture, then release them.
She plans to return in the event of more sightings, but there have been none since early January.
Shortnose sturgeon have been endangered since the passage of the Endangered Species Act in 1973 and even before, having been classified as such under the act’s predecessor, according to Wippelhauser.
The species appears to be on the rebound in Maine, she said. As the population grows, it spreads to other river systems. The sturgeon at the fish ladder probably came to the Damariscotta to feed, she said.
Wippelhauser attributes the rebound in part to the improvement of water quality in Maine since the 1970s.
The shortnose sturgeon, Acipenser brevirostrum, can grow up to 4.5 feet long and weigh up to 50 pounds, according to the National Marine Fisheries Service.
The fish live an average of 30 years, but can live up to 67, according to the fisheries service. Male shortnose sturgeon seldom exceed 30 years of age. At 3 feet and up, female shortnose sturgeon outnumber males 4-to-1.
The species’ diet includes shellfish, smelt eggs, and worms, according to Wippelhauser.
Maine Rivers describes the shortnose sturgeon as “a living fossil predating the dinosaur.”
“They are a primitive fish with rows of bony, armor-like plates on their sides and a skeleton of cartilage rather than bones,” according to Maine Rivers. “Sturgeon are bottom feeders – they suck plants and animals disturbed by their movement into their tube-like mouth.”
“The species rarely migrates far into the ocean away from its native river,” Maine Rivers says. “When ready to spawn, the sturgeon migrate upstream and deposit their eggs over gravelly or rocky river bottoms in moderately deep water with strong current.”
The range of the species runs from New Brunswick, Canada to Florida.